Wafer protection apparatus

ABSTRACT

A wafer protection apparatus for holding a wafer in a liquid. The wafer includes a first surface and a second surface opposite the first surface, and the second surface includes a first portion and a second portion. A reaction rate to the liquid of the second portion is faster than that of the first portion. The wafer protection apparatus comprises a first base, a second base, and a first sealing member. The first base holds the wafer in a manner such that the first base is in contact with the first surface of the wafer. The second base is connected with the first base. The first sealing member is disposed on the second base so as to abut the first portion of the second surface of the wafer.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a wafer protection apparatus; in particular, a wafer protection apparatus applied in a microelectromechanical process.

[0003] 2. Description of the Related Art

[0004] Microelectromechanical systems (MEMS) are microdevices widely used as advanced sensors, microfluidic controls, or micromachines. Advanced MEMS sensors can be found in automobiles, medical instrumentation, or process control applications, and provide accurate determinations of pressure, temperature, acceleration, gas concentration, and many other physical or chemical states. Microfluidic controls include microvalves for handling gases or liquids, flow gauges, and ink jet nozzles, while micromachines include microactuators, movable micromirror systems, tactile moving assemblies, and such devices as atomic force microscopy cantilevers. Commonly, microdevices are constructed from semiconductor material substrates such as crystalline silicon, widely available in the form of a semiconductor wafer used to produce integrated circuits.

[0005] Because of the commonality of material, fabrication of microdevices from a semiconductor wafer substrate can take advantage of the extensive experience in both surface and bulk etching techniques developed by the semiconductor processing industry for integrated circuit (IC) production. Surface etching, used in IC production for defining thin surface patterns in a semiconductor wafer, can be modified to allow for sacrificial undercut etching of thin layers of semiconductor materials to create movable elements. Bulk etching, typically used in IC production when deep trenches or vias must be formed in a wafer using anisotropic etch processes, can be used to precisely machine edges or trenches in microdevices. Both surface and bulk etching of wafers can proceed with “wet processing”, using chemicals such as potassium hydroxide in solution to remove non-masked material from a wafer. For microdevice construction, it is even possible to employ anisotropic wet processing techniques that rely on differential crystallographic orientations of materials, or the use of electrochemical etch stops, to define microdevice components. Unfortunately, freedom in designing complex microdevices is greatly constrained when wet processing etch techniques are used. Wet processing is severely limited by dependence on semiconductor crystal orientation and the materials and etchants used. Even worse, microdevices containing thin extending structures are often susceptible to damage as a result of hydrodynamic forces incurred during wet processing.

[0006] Thus, during wet processing, a wafer protection apparatus is provided to protect a specific area of the wafer. FIG. 1a shows a conventional wafer protection apparatus 10. The wafer protection apparatus 10 comprises a base 11, an O-ring 12, and two bolts 13. The base 11 holds a wafer 100. The O-ring 12 is disposed in the base 11 so as to form a space 14. The bolts 13 assemble the base 11 so that the base 11 is closely adjacent to the O-ring 12.

[0007] Referring to FIG. 1b, when the wafer protection apparatus 10, holding the wafer 100, is placed in an etchant 200, a surface 110 to be etched of the wafer 100 is in contact with the etchant 200, and a surface 120 not to be etched of the wafer 100 is protected by the space 14.

[0008] However, since the position of the O-ring 12 in the conventional wafer protection apparatus 10 is not proper, the surface 120 of the wafer 100 cannot be protected completely. Specifically, as shown in FIG. 1c, the etchant 200 can pass between the base 11 and the wafer 100, and between the O-ring 12 and the wafer 100 due to capillarity along an arrow. Then, the etchant 200 can etch a passivation layer on the surface 120 of the wafer 100. As a result, IC on the surface 120 is damaged by the etchant 200.

[0009] It is noted that the surface 110 of the wafer 100 is formed with a barrier layer 111 and an etching layer 112 by deposition or coating before etching. Since an etching rate to the etchant 200 of the barrier layer 111 is different from that of the etching layer 112, the surface 110 of the wafer 100 can be patterned.

SUMMARY OF THE INVENTION

[0010] In order to address the disadvantages of the aforementioned wafer protection apparatus, the invention provides a wafer protection apparatus that can enhance a manufactory yield in a MEMS process.

[0011] Accordingly, the invention provides a wafer protection apparatus for holding a wafer in a liquid. The wafer includes a first surface and a second surface opposite the first surface, and the second surface includes a first portion and a second portion. A reaction rate to the liquid of the second portion is faster than that of the first portion. The wafer protection apparatus comprises a first base, a second base, and a first sealing member. The first base holds the wafer in a manner such that the first base is in contact with the first surface of the wafer. The second base is connected with the first base. The first sealing member is disposed on the second base so as to abut the first portion of the second surface of the wafer.

[0012] In a preferred embodiment, the wafer protection apparatus further comprises a second sealing member. The second sealing member is disposed between the first base and the second base so as to prevent the liquid from passing between the first base and the second base due to capillarity.

[0013] In another preferred embodiment, the first sealing member may be of elastic material so as to closely abut the second base and the wafer respectively, and the second sealing member may be of elastic material so as to closely abut the first base and the second base respectively.

[0014] It is understood that the first sealing member and the second sealing member may be O-rings.

[0015] In another preferred embodiment, the second base includes a groove for the first sealing member to be disposed therein in a close fit manner.

[0016] In another preferred embodiment, the first base includes a step portion in a manner such that the first surface of the wafer faces the step portion to form a space therebetween.

[0017] In another preferred embodiment, the wafer protection apparatus further comprises a fixed member. The fixed member connects the first base and the second base so that the second base is closely adjacent to the first sealing member.

[0018] It is understood that the fixed member may be a bolt.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention is hereinafter described in detail with reference to the accompanying drawings in which:

[0020]FIG. 1a is a schematic view of a conventional wafer protection apparatus;

[0021]FIG. 1b is a schematic view that shows the wafer protection apparatus in FIG. 1a placed in an etchant;

[0022]FIG. 1c is a partial enlarged view in FIG. 1b;

[0023]FIG. 2 is a schematic view of a wafer surface to be etched;

[0024]FIG. 3a is a schematic view of a first embodiment of a wafer protection apparatus as disclosed in this invention;

[0025]FIG. 3b is a schematic view of a second base in FIG. 3a;

[0026]FIG. 3c is a cross section along a line c-c in FIG. 3b;

[0027]FIG. 4 is a schematic view that shows the wafer protection apparatus in FIG. 3a placed in an etchant;

[0028]FIG. 5a is a schematic view of a second embodiment of a wafer protection apparatus as disclosed in this invention; and

[0029]FIG. 5b is a schematic view that shows the wafer protection apparatus in FIG. 5a placed in an etchant.

DETAILED DESCRIPTION OF THE INVENTION

[0030] A wafer protection apparatus as disclosed in this invention holds a wafer in a liquid. The wafer protection apparatus can completely prevent a specific area of the wafer from contacting the liquid. The liquid may be an etchant, electroplating liquid, or others. In following embodiments, the etchant represents the liquid. Referring to FIG. 2, the wafer 100 includes a first surface 120 and a second surface 110 opposite the first surface 120. The first surface 120 is protected so as not to react with the etchant 200. The second surface 110 reacts with the etchant 200, and includes a first portion 111 and a second portion 112. The first portion 111 is a barrier layer, and the second portion 112 is an etching layer. A reaction rate to the etchant 200 of the first portion 111 is slower than that of the second portion 112.

[0031] First Embodiment

[0032] Referring to FIG. 3a, a wafer protection apparatus 20, as disclosed in a first embodiment of this invention, comprises a first base 21, a second base 22, a sealing member 23, and two fixed members 24.

[0033] As shown in FIG. 3a, the first base 21 is used as a main portion of the wafer protection apparatus 20, and holds the wafer 100 in a manner such that the first base 21 is in contact with the first surface 120 of the wafer 100. The first base 21 includes a step portion 211 in a manner such that the first surface 120 of the wafer 100 faces the step portion 211 to form is a space 25 therebetween.

[0034] The second base 22 is connected with the first base 21 by the fixed members 24. As shown in FIG. 3b and FIG. 3c, the second base 22 includes a groove 221 for the sealing member 23 to be disposed therein in a close fit manner.

[0035] The sealing member 23 is disposed in the groove 221 of the second base 22 in a close fit manner. The sealing member 23 maybe of elastic material, such as an O-ring. Thus, the sealing member 23 is closely adjacent to the first portion 111 of the second surface 110 of the wafer 100. As a result, the sealing member 23 can closely abut the second base 22 and the wafer 100 respectively.

[0036] The fixed members 24 connect the first base 21 and the second base 22 so that the second base 22 is closely adjacent to the sealing member 23. It is understood that the fixed members 24 may be bolts, respectively.

[0037]FIG. 4 shows the wafer protection apparatus 20 placed in the etchant 200. Since the sealing member 23 is closely adjacent to the first portion 111 of the wafer 100, only minute amounts of the etchant 200 can flow to a location between the wafer 100 and the sealing member 23 due to capillarity. Also, since the etching rate to the etchant 200 of the first portion 111 is extremely slow, the etchant 200 cannot flow to the first surface 120, located in the space 25, along an edge of the wafer 100. Thus, during the etching process, the etchant 200 is restrained from reacting with the second surface 110, and the first surface 120. As a result, the wafer protection apparatus 20 can protect the wafer 100 properly.

[0038] It is noted that each element of the wafer protection apparatus 20 is of a material that does not change its characteristics after contacting the etchant 200. Specifically, when the wafer protection apparatus 20 is placed in the etchant 200, the sealing member 23 is still closely adjacent to the second base 22 and the wafer 100, and the fixed members 24 still combine the first base 21 and the second base 22.

[0039] Second Embodiment

[0040] Referring to FIG. 5a and FIG. 5b, a wafer protection apparatus 30, as disclosed in a second embodiment of this invention, comprises a first base 31, a second base 32, a first sealing member 33, two fixed members 34, and a second sealing member 36. The difference between the first embodiment and the second embodiment is that the second sealing member 36 is added in this embodiment. Since the first base 31, the second base 32, the first sealing member 33, and the fixed members 34 of the second embodiment are the same as those of the first embodiment, their description is omitted.

[0041] The second sealing member 36 is disposed between the first base 31 and the second base 32, and may be of elastic material, such as an O-ring. Thus, the second sealing member 36 is closely adjacent to the first base 31 and the second base 32 respectively. As a result, the second sealing member 36 can prevent the etchant 200 from passing between the first base 31 and the second base 32 due to capillarity.

[0042] Since the wafer protection apparatus 30 includes the second sealing member 36, it can protect the wafer more effectively.

[0043] While the invention has been particularly shown and described with reference to preferred embodiments, it will be readily appreciated by those of ordinary skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. It is intended that the claims be interpreted to cover the disclosed embodiments, those alternatives which have been discussed above, and all equivalents thereto. 

What is claimed is:
 1. A wafer protection apparatus for holding a wafer in a liquid, wherein the wafer includes a first surface and a second surface opposite the first surface, and the second surface includes a first portion and a second portion, a reaction rate to the liquid of which is faster than that of the first portion, and the wafer protection apparatus comprises: a first base holding the wafer in a manner such that the first base is in contact with the first surface of the wafer; a second base connected with the first base; and a first sealing member disposed on the second base so as to abut the first portion of the second surface of the wafer.
 2. The wafer protection apparatus as claimed in claim 1, further comprising: a second sealing member disposed between the first base and the second base so as to prevent the liquid from passing between the first base and the second base due to capillarity.
 3. The wafer protection apparatus as claimed in claim 2, wherein the second sealing member is of elastic material so as to closely abut the first base and the second base respectively.
 4. The wafer protection apparatus as claimed in claim 3, wherein the second sealing member is an O-ring.
 5. The wafer protection apparatus as claimed in claim 1, wherein the first sealing member is of elastic material so as to closely abut the second base and the wafer respectively.
 6. The wafer protection apparatus as claimed in claim 5, wherein the first sealing member is an O-ring.
 7. The wafer protection apparatus as claimed in claim 1, wherein the second base includes a groove for the first sealing member to be disposed therein.
 8. The wafer protection apparatus as claimed in claim 7, wherein the first sealing member is disposed in the groove in a close fit manner.
 9. The wafer protection apparatus as claimed in claim 1, wherein the first base includes a step portion in a manner such that the first surface of the wafer faces the step portion to form a space therebetween.
 10. The wafer protection apparatus as claimed in claim 1, further comprising: a fixed member connecting the first base and the second base so that the second base is closely adjacent to the first sealing member.
 11. The wafer protection apparatus as claimed in claim 10, wherein the fixed member is a bolt.
 12. A wafer protection apparatus for holding a wafer in an etchant, wherein the wafer includes a first surface and a second surface opposite the first surface, and the second surface includes a first portion and a second portion, an etching rate to the etchant of which is faster than that of the first portion, and the wafer protection apparatus comprises: a first base holding the wafer in a manner such that the first base is in contact with the first surface of the wafer; a second base connected with the first base; and a first sealing member disposed on the second base so as to abut the first portion of the second surface of the wafer.
 13. The wafer protection apparatus as claimed in claim 12, further comprising: a second sealing member disposed between the first base and the second base so as to prevent the etchant from passing between the first base and the second base due to capillarity.
 14. The wafer protection apparatus as claimed in claim 13, wherein the second sealing member is of elastic material so as to closely abut the first base and the second base respectively.
 15. The wafer protection apparatus as claimed in claim 14, wherein the second sealing member is an O-ring.
 16. The wafer protection apparatus as claimed in claim 12, wherein the first sealing member is of elastic material so as to closely abut the second base and the wafer respectively.
 17. The wafer protection apparatus as claimed in claim 16, wherein the first sealing member is an O-ring.
 18. The wafer protection apparatus as claimed in claim 12, wherein the second base includes a groove for the first sealing member to be disposed therein.
 19. The wafer protection apparatus as claimed in claim 18, wherein the first sealing member is disposed in the groove in a close fit manner.
 20. The wafer protection apparatus as claimed in claim 12, wherein the first base includes a step portion in a manner such that the first surface of the wafer faces the step portion to form a space therebetween.
 21. The wafer protection apparatus as claimed in claim 12, further comprising: a fixed member connecting the first base and the second base so that the second base is closely adjacent to the first sealing member.
 22. The wafer protection apparatus as claimed in claim 21, wherein the fixed member is a bolt.
 23. A wafer protection apparatus for holding a wafer in an electroplating liquid, wherein the wafer includes a first surface and a second surface opposite the first surface, and the second surface includes a first portion and a second portion, a reaction rate to the electroplating liquid of which is faster than that of the first portion, and the wafer protection apparatus comprises: a first base holding the wafer in a manner such that the first base is in contact with the first surface of the wafer; a second base connected with the first base; and a first sealing member disposed on the second base so as to abut the first portion of the second surface of the wafer.
 24. The wafer protection apparatus as claimed in claim 23, further comprising: a second sealing member disposed between the first base and the second base so as to prevent the electroplating liquid from passing between the first base and the second base due to capillarity.
 25. The wafer protection apparatus as claimed in claim 24, wherein the second sealing member is of elastic material so as to closely abut the first base and the second base respectively.
 26. The wafer protection apparatus as claimed in claim 25, wherein the second sealing member is an O-ring.
 27. The wafer protection apparatus as claimed in claim 23, wherein the first sealing member is of elastic material so as to closely abut the second base and the wafer respectively.
 28. The wafer protection apparatus as claimed in claim 27, wherein the first sealing member is an O-ring.
 29. The wafer protection apparatus as claimed in claim 23, wherein the second base includes a groove for the first sealing member to be disposed therein.
 30. The wafer protection apparatus as claimed in claim 29, wherein the first sealing member is disposed in the groove in a close fit manner.
 31. The wafer protection apparatus as claimed in claim 23, wherein the first base includes a step portion in a manner such that the first surface of the wafer faces the step portion to form a space therebetween.
 32. The wafer protection apparatus as claimed in claim 23, further comprising: a fixed member connecting the first base and the second base so that the second base is closely adjacent to the first sealing member.
 33. The wafer protection apparatus as claimed in claim 32, wherein the fixed member is a bolt. 